Method and device for adapting and adjusting shear normal stiffness of soil structure interface

Abstract

The invention discloses a soil structure interface shear normal stiffness adaptation and adjustment method and device, and relates to the technical field of geotechnical engineering.The method comprises the steps that the stiffness of a to-be-measured soil body is measured through a stiffness adjustment module, and the stiffness of the to-be-measured soil body is adjusted according to the stiffness measurement result of the to-be-measured soil body; a plurality of mutually independent micro-spring unit bodies are mounted between the normal loading unit and the upper surface of the to-be-tested soil body; the rigidity of the micro-spring unit body is equal to the rigidity measurement result of the to-be-measured soil body, so that the normal rigidity of the boundary of the to-be-measured soil body in the shear test process is kept consistent with the rigidity of the to-be-measured soil body, and adaptation of the shear normal rigidity of the soil structure interface is completed; meanwhile, the pressure change condition of the soil body at each loading point in the shear test process of the to-be-measured soil body is measured in real time, a corresponding soil body pressure monitoring result is obtained, and whether the adaptive constant rigidity boundary meets a preset condition or not is verified through the soil body pressure monitoring result. According to the invention, more real constant rigidity boundary conditions of the soil body to be tested can be provided in the shear test process.

Description

Technical Field

[0001] The present application relates to the field of geotechnical engineering technology, and in particular to a method and device for adapting and adjusting the shear normal stiffness of a soil structure interface. Background Art

[0002] At present, the bearing capacity and stability of various underground structures are largely controlled by the soil-structure interface. Studying the shear deformation characteristics and ultimate failure performance of the soil-structure interface is of great significance for accurately designing the bearing capacity of underground structures and determining the deformation characteristics of underground structures. The relevant shear test equipment generally provides a constant normal stress boundary condition, that is, keeping the normal stress constant during the shear process, but the constant normal stress boundary condition is only applicable to the case where the interface deformation is relatively uniform during the shear process. However, in actual engineering, there are a large number of interfaces with uneven particle displacement. The rigid loading of the constant normal stress boundary condition will cause serious stress concentration during the loading process and is not applicable. However, the specimen deformation in the constant normal stiffness boundary condition is not limited by the loading plate, and the simulation of this situation is more accurate, that is, the normal stiffness of the soil to be tested is guaranteed to be constant during the shear process.

[0003] At present, the normal loading plate of the constant normal stiffness shear test equipment mostly adopts an integrated design, but the deformation of the tested soil during the shear process is not uniform. The relevant technology can only ensure the constant total stiffness and cannot provide suitable constant normal stiffness boundary conditions at each point. At the same time, the constant normal stiffness provided by the relevant equipment is a preset fixed value, which cannot be adapted to the actual stiffness of different tested soils, and still cannot reflect the true shear characteristics of the soil-structure interface during the shear process.

[0004] Therefore, it is necessary to provide a method and device for adapting and adjusting the shear normal stiffness of the soil structure interface to solve the above problems. Summary of the invention

[0005] The purpose of this application is to provide a method and device for adapting and adjusting the shear normal stiffness of a soil-structure interface, which can provide more realistic constant stiffness boundary conditions of the soil to be tested during a shear test.

[0006] To achieve the above objectives, this application provides the following solutions: In a first aspect, the present application provides a method for adapting and adjusting the shear normal stiffness of a soil structure interface, the method comprising: Before the shear test begins, the stiffness of the soil to be tested is measured using the stiffness adjustment module to obtain the stiffness measurement result of the soil to be tested; According to the stiffness measurement result of the soil body to be tested, a plurality of mutually independent microspring units are installed between the normal loading unit and the upper surface of the soil body to be tested; the plurality of microspring units form an array structure covering the upper surface of the soil body to be tested, and each of the microspring units can move independently; the stiffness of the microspring unit is equal to the stiffness measurement result of the soil body to be tested, so that the normal stiffness at the boundary of the soil body to be tested during the shear test is consistent with the stiffness of the soil body to be tested, and the adaptation of the shear normal stiffness of the soil structure interface is completed; At the same time, the pressure changes of the soil at each loading point during the shear test are measured in real time to obtain the corresponding soil pressure monitoring results, and the soil pressure monitoring results are used to verify whether the adapted constant stiffness boundary meets the preset conditions.

[0007] In a second aspect, the present application further provides a soil structure interface shear normal stiffness adaptation and adjustment device, the soil structure interface shear normal stiffness adaptation and adjustment device is used to implement the soil structure interface shear normal stiffness adaptation and adjustment method, the soil structure interface shear normal stiffness adaptation and adjustment device comprises: a discretized micro-spring stiffness adaptation assembly module and a stiffness adjustment module; The discrete microspring stiffness adaptation assembly module comprises: a plurality of mutually independent microspring units, each of which is installed between a normal loading unit and an upper surface of a soil body to be tested, and each of which is used to perform stiffness adaptation on the soil body to be tested at a corresponding loading point; A plurality of the microspring units form an array structure covering the upper surface of the soil to be tested, and each of the microspring units can move independently; The stiffness adjustment module is used for: Before the shear test begins, the stiffness of the soil to be tested is measured to obtain the stiffness measurement result of the soil to be tested; According to the stiffness measurement result of the soil body to be tested, the stiffness of the microspring unit is adjusted to be equal to the stiffness measurement result of the soil body to be tested, so that the normal stiffness at the boundary of the soil body to be tested during the shear test is consistent with the stiffness of the soil body to be tested, and the adaptation of the shear normal stiffness of the soil structure interface is completed; The pressure changes of each loading point of the soil to be tested during the shear test are measured in real time to obtain the corresponding soil pressure monitoring results, and the soil pressure monitoring results are used to verify whether the adapted constant stiffness boundary meets the preset conditions.

[0008] Optionally, the microspring unit body includes: an elastic unit and a micro-loading head, the elastic unit is respectively connected to the normal loading unit and the corresponding micro-loading head, each of the micro-loading heads is respectively in contact with the soil to be tested, the stiffness of each of the elastic units is adapted to the stiffness of the soil to be tested at the corresponding loading point, and each of the micro-loading heads moves independently.

[0009] Optionally, the size of each of the microspring units is less than or equal to 10 times the average particle size of the soil to be tested.

[0010] Optionally, the normal loading unit comprises: a normal loading head and a normal loading plate; The normal loading plate is located below the normal loading head, and the normal loading plate is connected to each of the elastic units; The normal loading head is used to apply a normal pressure of a preset magnitude to the elastic unit through the normal loading plate; The normal loading plate is used to disperse and apply the corresponding normal pressure to the corresponding elastic unit.

[0011] Optionally, a difference in stiffness between the normal loading plate and the soil to be tested is greater than a preset threshold.

[0012] Optionally, the elastic unit is a spring.

[0013] Optionally, the stiffness adjustment module includes: a soil stiffness testing element and a micro-spring unit stiffness regulating element; The soil stiffness testing element is installed on the shear box, and the microspring unit stiffness regulating element is located on the normal loading plate; The soil stiffness testing element is used to measure the stiffness of the soil to be tested before the shear test begins, and obtain the stiffness measurement result of the soil to be tested; The microspring unit stiffness regulating element is used to determine the stiffness of the microspring unit to be installed according to the stiffness measurement result of the soil body to be measured.

[0014] Optionally, the stiffness adjustment module further includes: A plurality of micro pressure test elements are fixed on the lower surface of the corresponding micro spring unit body, and are used to measure the pressure change of each point of the soil to be tested during the shear test in real time to obtain the corresponding soil pressure monitoring results.

[0015] According to the specific embodiments provided in this application, this application has the following technical effects: The present application discloses a method and device for adapting and adjusting the shear normal stiffness of a soil-structure interface. The method is based on the device for adapting and adjusting the shear normal stiffness of a soil-structure interface. The present application first measures the stiffness of a soil body to be tested before a shear test begins to obtain a stiffness measurement result of the soil body to be tested. Secondly, according to the stiffness measurement result of the soil body to be tested, a plurality of mutually independent micro-spring unit bodies are installed between a normal loading unit and an upper surface of the soil body to be tested, wherein the stiffness of the micro-spring unit bodies is equal to the stiffness measurement result of the soil body to be tested, so that the normal stiffness at the boundary of the soil body to be tested during the shear test is kept consistent with the stiffness of the soil body to be tested, and the adaptation of the shear normal stiffness of the soil-structure interface is completed, so that the present application can provide a more realistic constant stiffness boundary condition of the soil body to be tested during the shear test. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A schematic diagram of a flow chart of a method for adapting and adjusting the shear normal stiffness of a soil structure interface provided in one embodiment of the present application; Figure 2 A schematic diagram of a soil structure interface shear normal stiffness adaptation and adjustment device provided in one embodiment of the present application; Figure 3 A schematic diagram of an array arrangement of elastic units and micro-loading heads on a loading plate provided in an embodiment of the present application; Figure 4 A schematic diagram of a spring structure provided in an embodiment of the present application; Figure 5 A schematic diagram of a microspring unit stiffness control element provided in one embodiment of the present application.

[0018] Reference numerals: Upper shear box 1, lower shear box 2, soil to be tested 3, structural material 4, normal loading head 5, normal loading plate 6, elastic unit 7, micro loading head 8, first bending element 9, second bending element 10, tangential loading head 11, and micro pressure testing element 12. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0021] In an exemplary embodiment, Figure 1 As shown, a soil structure interface shear normal stiffness adaptation and adjustment method is provided, and the soil structure interface shear normal stiffness adaptation and adjustment method comprises: Step S1, before the shear test starts, the stiffness of the soil to be tested is measured using a stiffness adjustment module to obtain a stiffness measurement result of the soil to be tested.

[0022] Step S2, according to the stiffness measurement result of the soil body to be tested, a plurality of mutually independent micro spring units are installed between the normal loading unit and the upper surface of the soil body to be tested; Figure 2 , a plurality of the microspring units form an array structure covering the upper surface of the soil to be tested, and each of the microspring units can move independently; the stiffness of the microspring unit is equal to the stiffness measurement result of the soil to be tested, so that the normal stiffness at the boundary of the soil to be tested during the shear test is consistent with the stiffness of the soil to be tested, thereby completing the adaptation of the shear normal stiffness of the soil structure interface.

[0023] Step S3, at the same time, real-time measurement of the pressure change of the soil at each loading point during the shear test to obtain the corresponding soil pressure monitoring result, and verify whether the adapted constant stiffness boundary meets the preset conditions through the soil pressure monitoring result.

[0024] Further, based on the same inventive concept, Figure 2 As shown, the present application also provides a soil-structure interface shear normal stiffness adaptation and adjustment device, the soil-structure interface shear normal stiffness adaptation and adjustment device is used to implement the soil-structure interface shear normal stiffness adaptation and adjustment method, the soil-structure interface shear normal stiffness adaptation and adjustment device includes: a discrete microspring stiffness adaptation assembly module and a stiffness adjustment module.

[0025] The discrete microspring stiffness adaptation assembly module includes: a plurality of mutually independent microspring units, each of which is installed between the normal loading unit and the upper surface of the soil body to be tested, and the plurality of microspring units form an array structure covering the upper surface of the soil body to be tested, and each of the microspring units can move independently. During the interface shear process, it is ensured that the deformation of the soil body to be tested at each loading point is only affected by the surrounding soil body and is not restricted by the normal loading plate.

[0026] Each of the microspring units is used to perform stiffness adaptation on the soil to be tested at the corresponding loading point.

[0027] The stiffness adjustment module is used for: Before the shear test begins, the stiffness of the soil to be tested is measured to obtain a stiffness measurement result of the soil to be tested.

[0028] According to the stiffness measurement result of the soil to be tested, the stiffness of the microspring unit is adjusted to be equal to the stiffness measurement result of the soil to be tested, so that the normal stiffness at the boundary of the soil to be tested during the shear test is consistent with the stiffness of the soil to be tested, thereby completing the adaptation of the shear normal stiffness of the soil structure interface.

[0029] The pressure changes at each point of the soil to be tested during the shear test are measured in real time to obtain the corresponding soil pressure monitoring results, and the soil pressure monitoring results are used to verify whether the adapted constant stiffness boundary meets the preset conditions.

[0030] Optionally, the micro spring unit body includes: an elastic unit 7 and a micro loading head 8, wherein the elastic unit 7 is connected to the normal loading unit and the corresponding micro loading head 8 respectively, each of the micro loading heads 8 is in contact with the soil body to be tested respectively, the stiffness of each of the elastic units 7 is adapted to the stiffness of the soil body to be tested at the corresponding loading point, and each of the micro loading heads moves independently. The schematic diagram of the array arrangement of each of the elastic units 7 and the micro loading heads 8 on the normal loading plate 6 is shown in FIG. Figure 3 shown.

[0031] The micro-loading heads 8 are rectangular metal rigid structures. The thickness of each micro-loading head 8 is greater than the corresponding preset thickness threshold. The micro-loading heads 8 can slide relative to each other, and the thickness can ensure that the units are not misaligned.

[0032] The elastic unit 7 is used to apply corresponding normal pressure to the soil body 3 to be tested through the micro loading head 8. The stiffness of each elastic unit 7 is kept constant during the loading process, and the constant value can be pre-adjusted by replacing elastic units 7 with different stiffness.

[0033] Each of the micro-loading heads is used to apply the normal pressure received to the soil body 3 to be tested.

[0034] Optionally, the size of each of the microspring units is less than or equal to 10 times the average particle size of the soil to be tested.

[0035] Optionally, the normal loading unit comprises: a normal loading head 5 and a normal loading plate 6 ; wherein the normal loading unit is used to disperse and apply a normal pressure of a preset magnitude to each elastic unit 7 .

[0036] The normal loading plate 6 is located below the normal loading head 5 , and the normal loading plate 6 is connected to each of the elastic units 7 .

[0037] The normal loading head 5 is used to apply a normal pressure of a preset magnitude to the elastic unit 7 through the normal loading plate 6 .

[0038] The normal loading plate 6 is used to disperse and apply the corresponding normal pressure to the corresponding elastic unit 7. Each of the elastic units 7 is arranged on the lower surface of the normal loading plate 6, and is combined with the micro-loading head 8 to form a loading plane that is the same as the surface of the soil body 3 to be tested. Each elastic unit 7 can move independently, and the lower surface area of ​​a single micro-loading head 8 is as small as possible, thereby discretizing the plane finer, matching the shape of the soil body 3 to be tested more accurately, and the boundary conditions of the stiffness adaptation are more realistic (more in line with the natural conditions of the soil).

[0039] Optionally, a difference in stiffness between the normal loading plate 6 and the soil body to be tested is greater than a preset threshold.

[0040] Specifically, the rigidity of the normal loading plate 6 is much greater than the rigidity of the soil body 3 to be tested, and the normal loading plate 6 is an integrated flat plate with relatively large rigidity.

[0041] Optionally, the elastic unit 7 is a spring.

[0042] Specifically, according to the spring stiffness calculation formula, a spring with a suitable shape can be designed and replaced so that it has the same stiffness as the soil to be tested. The details are as follows: By changing the spring material, spiral diameter, wire diameter, pitch and other indicators, a series of springs with different stiffness can be obtained. By replacing the springs in different series and parallel combinations, the stiffness of the microspring unit can be changed to adapt to the stiffness of the soil sample.

[0043] Spring structure diagram Figure 4 As shown, Figure 4 Where D is the center diameter, D1 is the inner diameter, D2 is the outer diameter, t is the pitch, and d is the wire diameter (d=(D2-D1) / 2). The spring stiffness is calculated according to the following spring stiffness formula: .

[0044] Among them, G represents the shear elastic modulus, the unit is MPa; the wire diameter d is the unit of mm; n represents the effective number of turns, the unit is turns; the center diameter D is the unit of mm; K represents the spring coefficient, the unit is kg / mm.

[0045] When springs are connected in series, K=1 / (1 / K1+1 / K2); when springs are connected in parallel, K=K1+K2.

[0046] Optionally, the stiffness adjustment module includes: a soil stiffness testing element and a microspring unit stiffness regulating element.

[0047] The soil stiffness testing element is installed on the shear box, and the microspring unit stiffness regulating element is located on the normal loading plate.

[0048] The soil stiffness testing element is used to measure the stiffness of the soil to be tested before the shear test begins, and obtain the stiffness measurement result of the soil to be tested.

[0049] The microspring unit stiffness regulating element is used to determine the stiffness of the microspring unit to be installed according to the stiffness measurement result of the soil body to be measured. The schematic diagram of the microspring unit stiffness regulating element is as shown in Figure 5 shown.

[0050] Optionally, the stiffness adjustment module further comprises: a plurality of micro pressure test elements 12 fixed to the lower surface of the corresponding micro spring unit body, and the position of each micro pressure test element 12 is as follows: Figure 5 As shown in the figure, it is used to measure the pressure change of each point of the soil to be tested in real time during the shear test and obtain the corresponding soil pressure monitoring results. The soil pressure monitoring results obtained here are used to measure the shear band of the soil sample and reflect the evolution of the shear band of the soil. On the other hand, it is also a verification of the adaptive stiffness boundary.

[0051] In an exemplary embodiment, Figure 2 As shown, the soil structure interface shear normal stiffness adaptation and adjustment device also includes: an upper shear box 1, a lower shear box 2 and a tangential loading unit.

[0052] The lower shear box 2 is used for placing structural material 4 .

[0053] The upper shear box 1 is located above the structural material 4, and the upper shear box 1 is used to place the soil body 3 to be tested. The lower shear box 2 and the upper shear box 1 are made of metal, resin or plastic; the structural material 4 is one or a combination of soil-structure interface, concrete, soil and wood, soil and steel.

[0054] The tangential loading unit is arranged on the outer side wall of the lower shear box 2, and is used to apply horizontal pressure to the soil body 3 to be tested, so that the soil body 3 to be tested interacts with the structural material 4 to form a shear force.

[0055] Specifically, a constant normal stiffness boundary condition is applied to the soil body 3 to be tested through a discontinuous plane composed of a plurality of micro-loading heads 8. When the soil body 3 to be tested undergoes discontinuous deformation during the shearing process (such as the soil body 3 to be tested corresponding to the lower part of the micro-loading heads 8 bulges or sinks due to the shearing process), each micro-loading head 8 and the elastic unit 7 cooperate together to ensure that each point in the soil body 3 to be tested is adapted to the constant stiffness boundary condition. For example, when the soil body 3 to be tested corresponding to the lower part of the micro-loading head 8 bulges, the soil body 3 to be tested applies an extrusion force to the elastic unit 7 through the micro-loading head 8, and the micro-loading head 8 compresses the corresponding elastic unit 7. The elastic unit 7 is subjected to the extrusion force and contacts the normal loading plate 6 above, thereby avoiding the situation where the normal pressure is zero; during the shearing process, each micro-spring unit body of the soil body 3 to be tested corresponding to the lower part of each micro-loading head 8 can undergo shear deformation in a manner that is more in line with the natural real soil situation, and is not restricted by the micro-loading head 8.

[0056] As an optional implementation, the total area of ​​the lower surfaces of the plurality of micro-loading heads 8 is equal to the upper surface area of ​​the soil body 3 to be tested contained in the upper shear box 1 .

[0057] As an optional implementation, the loading surface area of ​​the normal loading plate 6 is equal to the upper surface area of ​​the soil body 3 to be tested.

[0058] As an optional implementation, the soil stiffness testing element includes: a first bending element 9 and a second bending element 10 .

[0059] The first bending element 9 is arranged at the center of the first side wall of the upper shear box 1 along the shearing direction, and the second bending element 10 is arranged at the center of the second side wall of the upper shear box 1 along the shearing direction. The first bending element 9 and the second bending element 10 are fixed to the corresponding side walls by drilling or gluing.

[0060] As an optional implementation, the interface area of ​​the structural material 4 contained in the lower shear box 2 is larger than the lower surface area of ​​the soil body 3 to be tested in the upper shear box 1 to ensure that the area of ​​the shear surface remains constant.

[0061] As an optional implementation, the tangential loading unit includes a tangential loading head 11 .

[0062] The tangential loading head 11 is arranged on the outer side wall of the lower shear box 2, and is used to apply horizontal pressure to the soil body 3 to be tested, so that the soil body 3 to be tested interacts with the structural material 4 to form a shear force. The tangential loading head 11 is fixed to the outer side wall of the lower shear box 2 by pins and rings.

[0063] Beneficial effects: (1) Before the interface shear test, the stiffness of the soil to be tested is measured, and the applied normal stiffness is adjusted to match it, which is more in line with the actual engineering situation. This stiffness adaptation method is not available in related technologies.

[0064] (2) A constant normal stiffness boundary condition is applied to the soil to be tested through a discontinuous plane composed of multiple micro-spring units. When the soil to be tested undergoes discontinuous deformation during the shearing process, each micro-loading head 8 and the elastic unit 7 cooperate with each other to ensure that each point in the soil to be tested is adapted to the constant stiffness boundary condition.

[0065] Based on the same inventive concept, the embodiment of the present application also provides a test method based on the soil structure interface shear normal stiffness adaptation and adjustment device involved above, including: (1) Installing the specimen: First install the prefabricated structural material 4 in the lower shear box 2, and then place the soil 3 to be tested in the upper shear box 1.

[0066] (2) Pre-compression and consolidation of the soil body 3 to be tested: The normal loading head 5 is operated by the control system to gradually apply normal pressure to the soil body 3 to be tested until a preset pressure threshold is reached (i.e., a preset normal pressure is finally applied).

[0067] (3) Measuring the stiffness of the soil body 3 to be tested: starting the soil stiffness measurement system to measure the stiffness of the soil body 3 to be tested under the corresponding normal pressure.

[0068] (4) Loading stiffness adaptation: Select the corresponding elastic unit 7 to make it the same as the measured stiffness of the soil body 3 to be tested, and then arrange it at the corresponding position.

[0069] (5) Interface shear test: The normal loading head 5 is operated by the control system to apply the corresponding normal pressure to the preset pressure threshold again, and the position of the normal loading plate 6 is maintained fixed. According to the test plan, the tangential loading head 11 is operated to complete the soil-underground structure interface shear test and obtain the corresponding shear test results.

[0070] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0071] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for adapting and adjusting the shear normal stiffness of a soil structure interface, characterized in that: The soil structure interface shear normal stiffness adaptation and adjustment method comprises: Before the shear test begins, the stiffness of the soil to be tested is measured using the stiffness adjustment module to obtain the stiffness measurement result of the soil to be tested; According to the stiffness measurement result of the soil body to be tested, a plurality of mutually independent microspring units are installed between the normal loading unit and the upper surface of the soil body to be tested; the plurality of microspring units form an array structure covering the upper surface of the soil body to be tested, and each of the microspring units can move independently; the stiffness of the microspring unit is equal to the stiffness measurement result of the soil body to be tested, so that the normal stiffness at the boundary of the soil body to be tested during the shear test is consistent with the stiffness of the soil body to be tested, and the adaptation of the shear normal stiffness of the soil structure interface is completed; At the same time, the pressure changes of the soil at each loading point during the shear test are measured in real time to obtain the corresponding soil pressure monitoring results, and the soil pressure monitoring results are used to verify whether the adapted constant stiffness boundary meets the preset conditions.

2. A soil structure interface shear normal stiffness adaptation and adjustment device, characterized in that: The soil structure interface shear normal stiffness adaptation and adjustment device is used to implement the soil structure interface shear normal stiffness adaptation and adjustment method described in claim 1, and the soil structure interface shear normal stiffness adaptation and adjustment device includes: a discretized microspring stiffness adaptation assembly module and a stiffness adjustment module; The discrete microspring stiffness adaptation assembly module comprises: a plurality of mutually independent microspring units, each of which is installed between a normal loading unit and an upper surface of a soil body to be tested, and each of which is used to perform stiffness adaptation on the soil body to be tested at a corresponding loading point; A plurality of the microspring units form an array structure covering the upper surface of the soil to be tested, and each of the microspring units can move independently; The stiffness adjustment module is used for: Before the shear test begins, the stiffness of the soil to be tested is measured to obtain the stiffness measurement result of the soil to be tested; According to the stiffness measurement result of the soil body to be tested, the stiffness of the microspring unit is adjusted to be equal to the stiffness measurement result of the soil body to be tested, so that the normal stiffness at the boundary of the soil body to be tested during the shear test is consistent with the stiffness of the soil body to be tested, and the adaptation of the shear normal stiffness of the soil structure interface is completed; The pressure changes of each loading point of the soil to be tested during the shear test are measured in real time to obtain the corresponding soil pressure monitoring results, and the soil pressure monitoring results are used to verify whether the adapted constant stiffness boundary meets the preset conditions.

3. The soil structure interface shear normal stiffness adaptation and adjustment device according to claim 2 is characterized in that: The microspring unit body includes: an elastic unit and a micro-loading head. The elastic unit is respectively connected to the normal loading unit and the corresponding micro-loading head. Each micro-loading head is respectively in contact with the soil to be tested. The stiffness of each elastic unit is adapted to the stiffness of the soil to be tested at the corresponding loading point. Each micro-loading head moves independently.

4. The soil structure interface shear normal stiffness adaptation and adjustment device according to claim 3 is characterized in that: The size of each microspring unit body is less than or equal to 10 times the average particle size of the soil to be tested.

5. The soil structure interface shear normal stiffness adaptation and adjustment device according to claim 3, characterized in that: The normal loading unit comprises: a normal loading head and a normal loading plate; The normal loading plate is located below the normal loading head, and the normal loading plate is connected to each of the elastic units; The normal loading head is used to apply a normal pressure of a preset magnitude to the elastic unit through the normal loading plate; The normal loading plate is used to disperse and apply the corresponding normal pressure to the corresponding elastic unit.

6. The soil structure interface shear normal stiffness adaptation and adjustment device according to claim 5, characterized in that: The difference in stiffness between the normal loading plate and the soil to be tested is greater than a preset threshold.

7. The soil structure interface shear normal stiffness adaptation and adjustment device according to claim 3 is characterized in that: The elastic unit is a spring.

8. The soil structure interface shear normal stiffness adaptation and adjustment device according to claim 5, characterized in that: The stiffness adjustment module includes: a soil stiffness test element and a micro-spring unit stiffness control element; The soil stiffness testing element is installed on the shear box, and the microspring unit stiffness regulating element is located on the normal loading plate; The soil stiffness testing element is used to measure the stiffness of the soil to be tested before the shear test begins, and obtain the stiffness measurement result of the soil to be tested; The microspring unit stiffness regulating element is used to determine the stiffness of the microspring unit to be installed according to the stiffness measurement result of the soil body to be measured.

9. The soil structure interface shear normal stiffness adaptation and adjustment device according to claim 8, characterized in that: The stiffness adjustment module also includes: A plurality of micro pressure test elements are fixed on the lower surface of the corresponding micro spring unit body, and are used to measure the pressure change of each point of the soil to be tested during the shear test in real time to obtain the corresponding soil pressure monitoring results.

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